This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-303618 filed on Oct. 3, 2000.
1. Field of the Invention
The present invention relates to a valve timing adjusting device for changing a valve timing of at least one of an intake valve and an exhaust valve of an internal combustion engine.
2. Description of Related Art
There has been conventionally known a vane-type valve timing adjusting device, in which a vane member rotating together with a camshaft is relatively rotatably housed in a housing member which is driven by a power from an engine crankshaft. The phase of the vane member with respect to the housing member, that is, a phase difference caused by relative rotation between the crankshaft and the camshaft, is hydraulically controlled, so that the valve timing of at least one of the intake valve and the exhaust valve is controlled.
In the valve timing adjusting device disclosed in JP-A-9-60507, within at least one of both end faces in the axial direction of the vane member, a groove passage for supplying the hydraulic fluid to a retard hydraulic chamber or an advance hydraulic chamber is formed.
In the valve timing adjusting device disclosed in JP-A-9-60507, the groove passage formed in at least one of the end faces of the vane member is not directly connected with the retard hydraulic chamber or the advance hydraulic chamber. The passage for supplying the hydraulic fluid from the groove passage into the retard hydraulic chamber or the advance hydraulic chamber is a hole passage formed in the vane member, through to be connected with the groove passage, by cutting with, for example, a drill.
The hole passage to be made in the vane member can not be formed by a molding process such as sintering or die-casting. Therefore, there will arise such a problem that it is necessary to use another hole passage forming process than the molding process, which will increase the number of processes for manufacturing the vane member. Besides, if drilling is used to form the hole passage, there will be left cutting chips and burrs, so that the addition of processes are needed for removing the chips and burrs.
Furthermore, when forming the groove passage in both end faces in the axial direction of the vane member, it will become necessary to form an oil passage through the vane member for the purpose of feeding the hydraulic fluid to the groove passage formed in the end face opposite to the hydraulic fluid supply side. Therefore, the number of manufacturing processes is increased.
An object of the invention to reduce the number of manufacturing process of a valve timing adjusting device.
According to a first aspect of the present invention, a retard passage and an advance passage are formed in at least one of an inner surface of a housing member and an outside surface of a vane member without forming a hole passage by drilling in the housing member and the vane member.
The retard passage and the advance passage are formed in at least one of the inner surface of the housing member and the outside surface of the vane member to which a hydraulic fluid is supplied from a fluid supply passage. Therefore, there is no need to form a hole through the housing member or the vane member in the axial direction, which connects the retard passage and the advance passage with the fluid supply passage.
The retard passage and the advance passage can be formed in at least one of the housing member and the vane member through the forming process such as sintering and die-casting. Therefore, it is possible to dispense with the process for forming, separately from the molding process, the retard passage and the advance passage by cutting or other.
According to a second aspect of the present invention, the retard passage is formed in one of the inner surface of the housing member and the outside surface of the vane member, and the advance passage is formed in the other member. The retard passage and the advance passage, therefore, can easily be formed.
To increase the torque to be received from the fluid pressure by the housing member and the vane member, the number of vanes must be increase. To gain a desired range of relative rotational angle, the vane and the shoe must be decreased in thickness in the rotation direction. With the vane and the shoe decreased in thickness rotation direction, it is desirable to mount a seal member on the forward end on the sliding side of the vane and the shoe decreased in thickness in the rotation direction, for the purpose of preventing leakage of the hydraulic fluid from the retard chamber and the advance chamber. The seal member mounted on the shoe, however, receives a centrifugal force in the radial direction in which the seal member will move away from the outer peripheral surface of the vane member. Therefore, if the seal member mounted on the shoe receives the fluid pressure further radially outwardly from the retard passage or the advance passage, the pressure pressing the seal member against the vane member will decrease, causing the hydraulic fluid to easily leak.
According to a third aspect of the present invention, in whichever phase of relative rotation the vane member is with respect to the housing member, the seal member mounted on the shoe does not reach either of the communication point of the retard chamber of the retard passage and the communication point of the advance chamber of the advance passage. The seal member mounted on the shoe does not receive the fluid pressure on the radially outer side from the retard passage or the advance passage, thereby preventing the hydraulic fluid leakage.